Carbide tool cutting characteristics

Carbide tools are powder metallurgy products sintered from high hardness, refractory metal compound powders (such as high temperature carbides such as WC, TiC, TaC, NbC) and metal binders (Co, Mo, Ni, etc.). Since the cemented carbide component contains a large amount of carbides having a high melting point, high hardness, and good chemical stability, the hardness, wear resistance, and heat resistance of the cemented carbide are high. The normal temperature hardness of cemented carbide is generally 89~93HRA, which is equivalent to 78~82HRC. The allowable cutting temperature is as high as 800°C~1000°C. Even at 540°C, the hardness is still 77~85HRA, which is equivalent to the normal temperature hardness of high speed steel. . Therefore, the cutting performance of cemented carbide is much higher than that of high-speed steel. Under the same durability, the allowable cutting speed of cemented carbide is 4 to 10 times higher than that of high-speed steel, and the cutting speed can reach 100m/min or more. All kinds of difficult-to-machine materials such as hardened steel that can not be cut by high-speed steel tools. However, due to its low flexural strength (about 1/2~1/4 of high speed steel) and impact toughness (about 1/8~1/30) and poor workmanship, the current hard alloy The material is mainly used in the manufacture of non-interrupted cutting tools with simple blade shape and no impact. When the carbide content in cemented carbide is high, the hardness is high, but the bending strength is relatively low; When the content is high, the bending strength is higher and the hardness is lower. ISO classifies cemented carbide into three major categories: P, K and M. The main components of the three types of cemented carbide are WC, so they are collectively referred to as WC-based hard alloy. K class is equivalent to tungsten-cobalt cemented carbide, codenamed YG, mainly composed of WC and Co. YG-type cemented carbide has good flexural strength and impact toughness, suitable for processing of brittle materials. It can be used for the processing of cast iron, non-ferrous metals and their alloys and non-metallic materials. YG-type hard alloys have lower hardness with increasing cobalt content, and the flexural strength is increased, and the ability to withstand impact is enhanced. Processing, on the contrary, the hardness, wear resistance and heat resistance increase, suitable for finishing. China's tungsten-cobalt-titanium cemented carbide, codenamed YT, contains 5% to 30% TiC in addition to WC and Co. Since the hardness and melting point of TiC are higher than WC, the hardness of such cemented carbide The wear resistance and heat resistance are higher than those of YG, while the flexural strength and impact toughness are slightly lower. With the increase of TiC content, the hardness, heat resistance and wear resistance of the material are getting better and better. Bending strength and impact toughness are reduced. YT-type cemented carbide can generally be used for high-speed cutting of steel. M is equivalent to China's tungsten-titanium-niobium (铌) cobalt-based hard alloy, codenamed YW, which is in the above A certain amount of TaC or NbC is added to the cemented carbide component to improve the high temperature hardness, high temperature strength and wear resistance of the cemented carbide material. The YW type is characterized by good comprehensive performance and wide application range, and can be used for various cast iron and steel. Processing of materials, stainless steel and superalloys.